7.1 Common Routing ConfigurationsFirst, we must make a distinction between routing and routing protocols. All systems route data, but not all systems run routing protocols. Routing is the act of forwarding datagrams based on the information contained in the routing table. Routing protocols are programs that exchange the information used to build routing tables. A network's routing configuration does not always require a routing protocol. In situations where the routing information does not change for example, when there is only one possible route the system administrator usually builds the routing table manually. Some networks have no access to any other TCP/IP networks and therefore do not require that the system administrator build the routing table at all. The three most common routing configurations[1] are the following.
Routes are built manually by the system administrator or dynamically by routing protocols. But no matter how routes are entered, they all end up in the routing table. |